textproduct: Albany

WHAT HAS CHANGED

The slight risk (level 2 of 5) for severe weather on Saturday has expanded into areas near and south of I-90 with damaging winds the primary hazard from any severe storms.

Earlier arrival of clouds and showers/storms on Saturday has resulted in temperatures trending lower compared to the previous forecast. Thus, the potential for heat-related impacted has lowered.

KEY MESSAGES

1) While temperatures remain above normal today and tomorrow, the chance for heat-related impacts has trended lower across eastern NY and western New England.

2) There is a marginal (level 1 of 5) and slight risk (level 2 of 5) for isolated to scattered severe thunderstorms across eastern New York and western New England tomorrow and tomorrow evening. Primary hazards from any severe storm are damaging winds and heavy downpours.

3) Increasing confidence for temperatures to trend above normal for the end of next week.

DISCUSSION

KEY MESSAGE 1...

Upper level ridging remains parked over the Northeast today but starts to weaken as a trough develops over the Canadian Prairie and Great Lakes. Westerly flow on the northern periphery of the ridge will advect a warmer air mass into the Northeast with 850hPa isotherms reaching +14C to +16C and allow mid and upper level moisture to spill overhead. While there is medium to high confidence that rather deep boundary layer mixing will support temperatures warming into the mid to upper 80s in valley areas with even around 90 in the mid-Hudson Valley, low humidity will once again limit heat-related impacts. The increasing cirrus canopy has also lowered the potential for temperatures to exceed 90 degrees with the potential limited to just a 10 to 30% chance in the mid-Hudson Valley. The latest HeatRisk for today remains moderate (level 2 of 4) meaning populations sensitive to the heat (i.e those without cooling) may be affected. Regardless, it is still recommended to avoid unnecessary strenuous activity and to remain hydrated. Clouds increase and lower tonight into tomorrow as the trough approaches. While moisture and therefore humidity will trend higher, clouds and increasing chances for showers/storms will likely keep temperatures a few degrees lower compared to today. There is still a low chance for temperatures to reach 90 degrees in the mid-Hudson Valley as showers/storms will likely hold off until Saturday afternoon. This plus the higher humidity will make it feel more like the low-90s but the potential to reach heat advisory criteria (heat index at or above 95F) has lowered.

KEY MESSAGE 2...

Height falls spread from west to east across eastern NY and western New England late tonight and through the day tomorrow as our trough approaches from the Great Lakes. The leading edge of the height falls and mid-level moisture reaches areas mainly north/west of the Capital District late tonight into Saturday morning with the latest probabilistic guidance showing a 30 to 60% chance for measurable rainfall through this period with even a 50 to 75% chance in the southwest Adirondacks. Areas south of I-90 remain drier through Saturday morning where there is less than a 40% chance for measurable rainfall. However, there is greater than a 75% chance for measurable rainfall regionwide Saturday afternoon into early evening. Overall forcing is not particularly strong between gradual height falls aloft and a weak pre-frontal trough at the sfc so not expecting a washout. In fact, showers should be scattered in nature with breaks of dry time.

The higher humidity values and limited insolation will yield weak instability sufficient to generate some thunderstorms with probabilistic guidance still showing surface based CAPE values mainly near or under 1000 J/kg. With PWATs >1.5" and forecast soundings showing a tall, skinny CAPE signature, thunderstorms will be capable of heavy downpours. Despite meager instability, a conveyor belt of faster, confluent flow aloft spreading eastward will support strong enough deep layer shear values 25-35kts capable of organized convection. With shear vectors oriented mainly parallel or slightly perpendicular to the pre-frontal trough, expecting a linear storm mode or storm clusters with damaging winds the primary hazard from any severe weather. The Storm Prediction Center has expanded the slight risk (level 2 of 5) in its Day 2 Outlook for Saturday across areas mainly near and south of I-90 where there should be a more favorable overlap of instability and shear combined with slightly steeper mid-level lapse rates. Chances for severe weather diminish Saturday night. Additional scattered areas of showers/storms are likely on Sunday as the upper level tough and cold pool track overhead but severe weather is unlikely given lower instability.

KEY MESSAGE 3...

While temperatures turn cooler Sunday and Monday, there is increasing confidence for temperatures to trend above normal once again for the middle and especially at the end of next week. Guidance suggests a heat dome develops in the Central CONUS (850hPa isotherms about 2 standard deviations above normal per the NAEFS) for the middle of next week. As ridging builds eastward towards the end of the week into next weekend, there is increasing consensus that the anomalously warm air mass advects into the Northeast. Latest probabilistic guidance shows greater than a 75% chance for temperatures to exceed 90 degrees in valley areas next Friday and Saturday. We will continue to monitor trends for impactful heat.

AVIATION /12Z FRIDAY THROUGH TUESDAY/

Through 12z/Saturday...VFR conditions are expected to continue across all terminals through the entire 24 hour TAF period. Few and scattered high level cirrus passes through today with mid and low level clouds increasing coverage towards the end of the TAF period. Calm winds become 5-10 kt from the south/southwest at KGFL and west/northwest at KALB, KPOU, and KPSF by around noon. Winds then taper off with sunset generally remaining near 5 kt or less overnight.

Outlook...

Saturday Night: High Operational Impact. Numerous SHRA...TSRA. Sunday: High Operational Impact. Breezy. Likely SHRA...TSRA. Sunday Night: Low Operational Impact. Breezy. NO SIG WX. Monday: No Operational Impact. NO SIG WX. Monday Night: No Operational Impact. NO SIG WX. Tuesday: No Operational Impact. NO SIG WX. Tuesday Night: No Operational Impact. NO SIG WX. Wednesday: Low Operational Impact. NO SIG WX.MA...None.

ALY WATCHES/WARNINGS/ADVISORIES

CT...None. NY...None. MA...None. VT...None.